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Title: Amp buzzing, Ground noise?? Post by: Zenguitarguy on November 09, 2008, 05:25:32 PM My Ot is amazing, sounds great but it buzzes. When I opened it up the polarity switch was not connected. Nik sent me a diagram to follow to wire it explaining that he does not ship ground wired as it is apparently illegal in some countries?
Anyway, my tech came over, as i am not technical in this capacity, and we tried to wire the polarity switch. i sent this email to Nik; "the amp does not seem to match the diagram you sent. the zero point of the transformer primary is wired directly to the neutral pin of the AC inlet, which is not what is on the diagram. The diagram has it going to the fuse. We are trying to follow and match the diagram but it is not making sense." We ended up re-wiring to match the diagram, spent 2 hours trying, but nothing, the hum is still there and the polarity switch does nothing. This hum, definitely 60hz, is more pronounced in gain channel, it is there at same amplitude whether a guitar is plugged in or not, my guitars have John suhr Pups with backplate, no computers, rf, or other noise generators in proximity. Please email me with any suggestions. Thanks Title: Re: Amp buzzing, Ground noise?? Post by: erwin_ve on November 09, 2008, 05:56:00 PM Hum can be caused by various reasons;
-heater wires can cause problems when touching/ run to close, to other wires. -bad tube -leaking filter caps -ground loops You can easily check if it's " 1.pre-amp or 2.power-amp or 3.all-over amp" hum. 1.plug your guitar in the OTS amp, put a cable in the send and wire the signal from the send to an other amps fx-loop. Power-amp is then bypassed. 2. Bypass the pre-amp by putting a signal in the return of the OTS. Title: Re: Amp buzzing, Ground noise?? Post by: mcinku on November 09, 2008, 06:49:41 PM 1.plug your guitar in the OTS amp, put a cable in the send and wire the signal from the send to an other amps fx-loop. Power-amp is then bypassed. 2. Bypass the pre-amp by putting a signal in the return of the OTS. Just want to say that a test like that can make ground loop hum even worse. So you might want to consider lifting a ground, on one device while doing this. This guy can explain it better than me... http://www.youtube.com/watch?v=4YM1iwC6vhg (http://www.youtube.com/watch?v=4YM1iwC6vhg) ;) Title: Re: Amp buzzing, Ground noise?? Post by: erwin_ve on November 09, 2008, 06:57:35 PM True! :-[ My bad.
Title: Re: Amp buzzing, Ground noise?? Post by: Zenguitarguy on November 09, 2008, 07:29:12 PM Hmnnnn not sure as I expect to hear amp blow but not so much buzz, it is challenging chasing this down, but weird that i cannot connect the polarity switch, hmnnnn, keep those ideas coming!! and thanks
Title: Re: Amp buzzing, Ground noise?? Post by: mcinku on November 10, 2008, 06:55:57 AM Here's a page with some more ideas about the hum...
http://www.geofex.com/ampdbug/hum.htm (http://www.geofex.com/ampdbug/hum.htm) ;) Title: Re: Amp buzzing, Ground noise?? Post by: Mike on November 10, 2008, 06:03:46 PM I know it does not help very much, but at least you're not alone. Mine has the same efffect and its not a ground loop. I fed the amp even with synthesized power from a PS Audio Power Plant, but the hum persists. The hum increases in relation to the Master Volume alone - even without a guitar plugged in. I have a Klein in the fx loop and if this is set at send 1:00, return fully open, recovery 12:00 I may use the master at 4 (11:00) without considerable hum either. Without the Klein and above settings, hum sets in above master=2 and gradually increasing as you turn up the master. This is all for the clean channel, no OD.
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